1. Field of the Invention
The present invention relates to a control apparatus of an internal combustion engine mounted in a vehicle.
The present invention particularly relates to an output control function of a control apparatus to control output of an internal combustion engine having an electronic throttle system based on operating conditions of an accelerator pedal and a brake pedal, which are operated intentionally.
2. Description of the Related Art
A control apparatus of an electronic throttle system takes in an accelerator opening detected by an accelerator sensor (accelerator opening sensor) as an input, and calculates a target throttle opening as a control output based on this accelerator opening or a combination with other conditions.
A throttle is controlled and driven to open and close by a motor so as to correspond (in other words, “converge”) to the target throttle opening. An actual driving amount (control amount) of the motor is a difference between an immediately preceding throttle opening position and a target throttle opening position.
In the control apparatus of the electronic throttle system, whether the actual throttle opening corresponds (converges) to the target throttle opening or not is detected with a throttle sensor, and feedback control is performed so that the opening corresponds (converges) thereto.
Further, there is a technique to set the throttle opening to limp home (also called “limp home opening”) in case of system failure or abnormal condition, as described in prior arts of Japanese Patent No. 3464918, Japanese Patent No. 3547619, Japanese Patent No. 3820643, Japanese Laid-open Patent Publication No. 11-343909, Japanese Laid-open Patent Publication No. 2002-235595, and Japanese Laid-open Patent Publication No. 2007-198159.
Further, in the above documents, there are techniques to control the throttle opening according to a brake operation. These techniques are to use the brake as an input unit alternative to the accelerator, or to use the brake as a trigger input for stopping the function.
Now, in consideration of the case where the accelerator pedal is caught in a floor mat, or the like, the conventional control apparatus of the internal combustion engine fixes the accelerator opening for control to an IDL opening (approximately equal to full close) when both the accelerator and the brake are pressed down.
However, in the conventional control, when pressing down on the accelerator pedal is not released, the accelerator opening is kept fixed to the IDL opening and causes braking. Accordingly, there is a disadvantage that retreat traveling is not possible in this state.
At this time, when pressing down on the brake pedal is released, acceleration of the vehicle is possible, but the engine output is high according to the accelerator opening caused by the pressing down. Thus, there is a disadvantage that it is very difficult to adjust the speed while switching between the two opposite extreme states.
Further, when determination of braking is performed only with a brake switch as illustrated in FIG. 7, the control would not be able to function when just the brake switch fails. Thus, for reliability of control, there is a disadvantage that there remains uncertainty in determination only with the brake switch.
Further, all of the techniques in the above documents are applied in case of failure (after a failure is determined), or abnormality (after abnormality is determined). Accordingly, there is a disadvantage that the control would not be able to function unless some kind of cause of a problem (specific device) is clearly determined.
That is, only with system components of the conventional electronic throttle systems, it is difficult to judge whether it is a pedal operation amount by an intentional operation or a pedal operation amount based on an accidental external cause such as being caught in a mat. However, increasing and complicating system components of the electronic throttle system by adding a system component, which does not contribute to a normal traveling, just for the purpose of detecting an accidental external cause is also not favorable.
Moreover, also regarding the technique to perform control according to a brake operation, it is still not possible to satisfy all of a traveling state accompanying an intentional operation with both feet, fail safe under an abnormal condition (also called “retreat traveling state”), and wrong pressing (operating both the accelerator and the brake) done unconsciously, or the like.